(i) Reaction of ' A ' with Ag2O to give ppt indicates −C≡ CH type of linkage. (ii) Going backward in the second set, compound ' C ' when heated with ZnCl, and conc. HCl gives turbidity within 5 minutes, it indicates that 'C′ is a 2∘ alcohol, (C) hence 'B' is a ketone and ' A ' is prop-1-yne.